Environment: Definition and Four Components
In simple words, environment is defined as the natural world in which people, animals and plants live. The term Environment is derived from French terms ‘virer (to turn) or ‘in/viron’ meaning to encircle; and denotes the interaction between natural surroundings and organisms including human beings. Thus, environment is the surroundings in which living and non-living things live, interact, grow and perish. The conditions present in the surroundings govern the life of creatures therein.
Four Components of Environment
The four major components of environment include lithosphere, hydrosphere, atmosphere and biosphere, corresponding to rocks, water, air and life respectively.
- Lithosphere is the outermost layer of earth called crust, which is made of different minerals. Its depth can reach up to 100 kilometers and is found on both land (terrestrial crust) and oceans (oceanic crust). The main component of lithosphere is earth’s tectonic plates.
- Hydrosphere comprises of all forms of water bodies on earth including oceans, seas, rivers, lakes, ponds, streams etc. It covers 70% of earth’s surface. 97.5% of water found on Earth is in the oceans in the form of salt water. Only 2.5 % of water on Earth is freshwater. Out of this, 30.8% is available as groundwater and 68.9% is in frozen forms as in glaciers. Amount of 0.3% is available in rivers, reservoirs and lakes and is easily accessible to man.
- Atmosphere is gaseous layer enveloping the Earth. The atmosphere with oxygen in abundance is unique to Earth and sustains life. It mainly comprises 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, and traces of hydrogen, helium, and noble gases. The amount of water vapour present is variable.
- Biosphere refers to all the regions on Earth where life exists. The ecosystems that support life could be in soil, air, water or land. The term Biosphere was coined by Geologist Edward Suess who used this term for place on Earth where life can be found. Biosphere refers to the sum total of all living matter, the biomass or biota. It extends from the polar ice caps to the equator, with each region harboring some life form suitable to the conditions there.
Environmental science is an interdisciplinary subject. It draws from a whole gamut of subjects like geography, geology, biology, chemistry, physics, botany, zoology, genetics, sociology, rural development, urban planning, policy development, politics, cultural studies, economics, ethics, law, education, health, communication and philosophy. It is a science that will address the biggest challenges encountering the planet in this millennium. It studies the complex interaction of human with nature and provides guidelines for the way forward.
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